We turn now to what some are calling a high tech nightmare playing out at security checkpoints across this country. It involves do it yourself plastic guns, and they work. And they're slipping past metal detectors. And here's abc's senior justice correspondent pierre thomas. Reporter: What you're looking at is not a toy. Virtually all plastic. Able to defeat metal detectors. Lethal. Tested as an effective viable killing weapon by the atf. Some of its bullets may not have enough metal to set off a metal detector. Courthouses, major sporting events, all vulnerable. A firearm like this can defeat hundreds of thousands of dollars that an arena or courthouse has invested in security. Reporter: Case in point. An israeli tv station made a plastic gun and was able to smuggle it right past security into a room with prime minister netanyahu. Look at that. Gun and prime minister only feet away. And what also has police concerned is that these guns can be made at home. They can be produced from commercially available 3d printers that literally build three dimensional parts from plastic materials. The blueprint for how to make such a gun has been posted online. You can legally produce such a weapon as long as you include several ounces of metal. Problem is, that metal can be easily removed. With this metal block, this weapon is perfectly legal. But if you remove it, this gun becomes invisible, undetectable. An assassin's dream. And an even bigger problem. Current federal law regulating undetectable guns is set to EXPIRE DECEMBER 9th. Then, such a gun can be manufactured with no meaningful requirement for metal. So the potential exists for a black market of undetectable, untraceable, dangerous guns. A security nightmare. Pierre thomas, abc news, washington.

This transcript has been automatically generated and may not be 100% accurate.

Now Playing: Aaron Hernandez Trial: Patriots Owner Robert Kraft Called as a Surprise Witness

Now Playing: Nine Crew Members From Tourist Pirate Ship Rescued in Stormy Waters

{"id":20919257,"title":"3D Printed Guns Pose New Threat as Gun Law Expires","duration":"1:48","description":"Virtually all-plastic guns able to defeat metal detectors without a trace.","url":"/WNT/video/3d-printed-guns-pose-threat-gun-law-expires-20919257","section":"WNT","mediaType":"Default"}